Its not the size as in length x width, its the file size (quality) thats too big.
If you have Photoshop crop the pic so it includes only the subject you really want to show, then resize it to about 8"x6" (both of these features are under the "image" tab).
Finally do a save as, after renaming the pic the final step is Image Options, here you specify if you want a high quality pic (large file) or lower quality pic (small file), the final size will be displayed at the bottom of the screen to the left. To imbed the pic in your post the easy way (the "click here to upload" and "imbed pic in post" options)the file has to be <100k.
There is a way to post large files by using a hosting service and linking to it but its trickier than what I outlined above.

Also, I don't mind helping out but in the future pls post these questions in the Off Season forum, the folks down there have alot of time on there hands and these posts wouldn't be off topic there.